The present invention relates to a vehicle seat, particularly to a vehicle seat having a light weight and an good rigidity.
When a vehicle such as a motor vehicle impacted from the front side, the rear side, and the side, due to inertia force, a passenger is moved in the colliding direction of forward, rearward, and sideward, respectively, relative to the vehicle. Since a great shock is given to the passenger at this time, there is a need for ensuring safety of the passenger.
When the vehicle is impacted from the front side, the rear side, and the side, a technique of absorbing a load at the time of collision, that is, collision energy by a buffer structure (such as an engine room and a console box) provided on the vehicle body side to ensure the safety of the passenger is used. In order to transmit such collision energy to the vehicle body side to be absorbed, there is a need for enhancing rigidity of a vehicle seat on which the passenger is seated to efficiently transmit the collision energy to the vehicle body side.
When the vehicle is impacted from the rear side, and when baggage or the like is placed on the rear side of the passenger, the baggage is rapidly moved forward due to the inertia force. Thus, there is a need for protecting the passenger from a colliding object such as the baggage. Further, when the vehicle is impacted from the rear side, a body of the passenger is moved rearward. Thus, there is a need for reliably holding the body of the passenger by way of the vehicle seat. Therefore, in view of protecting the passenger from the colliding object, there is also a need for enhancing the rigidity of the vehicle seat.
In the vehicle seat, there is a need for providing the rigidity in order to hold a seating space of the passenger and to ensure the safety of the passenger without deformation not only due to the shock in the front and rear direction but also shock energy when the vehicle is impacted on a side surface.
Japanese Patent Application Publication No. 2008-514490 (“the '490 Publication”) relates to a seat back structure for a vehicle seat and discloses a vehicle seat in which plate shaped front and rear shells formed into a seat back shape are arranged to face each other and adhered to each other.
With such a configuration, the rigidity against the shock in the front and rear direction and the left and right direction (the seat width direction) is enhanced in the seat back of the vehicle seat.
The technique disclosed in the '490 Publication discloses a configuration that the plate shaped front and rear shells respectively arranged in the front and rear direction are adhered to each other in a seat back frame.
However, the technique of the '490 Publication discloses the configuration that two plate shaped members having size of the seat back frame are adhered to each other. Thus, there is a disadvantage that weight of the entire seat is increased.
By reducing plate thickness of the front and rear shells, the seat back frame can have a lighter weight. However, rigidity of the front and rear shells is lowered, so that there is a problem that strength is lowered when a load in the front and rear direction and the left and right direction is imposed.